The present invention relates to a camera, and in particular, the present invention relates to a viewfinder of a single lens reflex ("SLR") camera.
Viewfinders of single lens reflex cameras which display various types of information superposed on a subject image on a screen are generally known. The information is displayed using a guest-host system, or similar liquid crystal display positioned adjacent to a screen surface, or by irradiating light from a light emitting diode ("LED"), or similar device, to a microprism adjacent to the screen surface and displaying the resulting reflected light.
Since both the liquid crystal display and the microprism must be located between the screen surface and a pentaprism of the viewfinder, the amount of available space between the screen surface and the pentaprism is limited. Given the limit in available space, and since both the liquid crystal display and microprism are relatively thick, designing a viewfinder that utilizes a liquid crystal display and a microprism has proven to be difficult.
In addition, while irradiating light from an LED onto the microprism results in a clear illumination of a display in the viewfinder, flare tends to originate in light diffused by the microprism, corrupting the display. In order to prevent such flare from occurring, it is necessary to employ additional elements, such as a screen surface or a Fresnel lens as a condenser. Nevertheless, because the screen tends to be positioned within relative close proximity to the display portion, diffusion of light beams inevitably occurs, making it difficult to design a viewfinder that prevents flare from occurring.
Furthermore, since the display can typically be changed only by activating an ON-OFF portion of a preset button, the information which can be displayed is limited to photographic information related to an autofocus operation.